Process and apparatus for the production of sulphur trioxide



Aug. 21, 1934. w. L. SPALDING 1,970,923.

PROCESS AND MPAIiATUS FOR THE PRQDUCTION OF SULPHUR TRIOXIDE Filed July 7, 1931 STE/1M A? 20 22 z/ /a m I Ah (3, NW

by admixing volumes of Patented Aug. 21, 1934 PROCESS AND APPARATUS FOR THE PRO- DUCTION OF SULPHUR TRIOXIDE William L. Spalding, Westfield, N. J assignor to American Gyanamid Company,

New York,

N. Y., a corporation of Maine Application July 7, 1931, Serial No. 549,197 11 Claims. (01. 23-176)- This present invention relates to a method and apparatus for efficiently and thoroughly mixing or oommingling bodies application in the manufacture of sulphuric acid sulphur dioxide and air, and passage of this mixture through catalytic contact material for the production of sulphur trioxide, which is subsequently converted to H2304. While the invention is particularly applicable to 10v the sulphuric acid art and solves a real problem there, yet obviously it has many' other applications and may be used in any circumstances where it is desired to cause efficient and'th'orough mixingor commin'gling of at least two bodies of gases, particularly over a large area while traveling a comparatively short forward distance, and where it is desired to'redistribute the mixed gases uniformly overthis area.

In the manufacture of sulphuric acid by passing sulphur dioxide and air through contact cataby this catalytic reaction develops a considerable amount of heat. Inasmuch as the reaction proceeds most efficiently within a comparatively small temperature range, and this developed heat raises the temperature of the'gases to a point outside of this range, it becomes desirable, if the efficiency of the reaction is to be maintained, that these gases be cooled to a point within the efiicient reactionrange prior to their passage through additional or subsequent catalytic material.

It has been found desirable in the production of sulphuric acid as above set forth to provide'an admixturewith sulphur dioxide, over that necessary to theoretically combine with the latterto form sulphur trioxide. If this total excess amount of air is initially added to the sulphur dioxide and the mixture passed through successive masses of contact material, a much less efiicient reaction is obtained, than if a minimum excess were added prior tothe passage through'the first-contact mass and an additional excess added to these gases prior to their introduction to the second or next contact mass, unless in'the former case, the gas is cooled as by contact with cooledmetallic surfacesafter passing through each mass.

The patent to Ferguson 723,595 proposes broadly to solve the above difficulties. Burner gas containing sulphur dioxide is introduced to the first of three chambers with some air, and additional quantities of air are added intoa mixing pipe connecting the several chambers and subsequent to the passageof the mixture of gases. It has specific Actual operations have demonstrated i w hin short lengths j converter chambers. using but a single chamber, the Ferguson arrangeexcess amount of oxygen as air or other gas forwhich will permit of the maintenance of the gases within the desired conversion temperature through one of the chambers. This" added air serves two functions, to wit, it cools down the highly heated gas resulting from its passage through the first series of contact masses, and

second, it permits of the operation of each of thehl) converters with minimum quantities of excess air rather than adding the entire amount of 'air necessary prior to the first converter.

The Ferguson patent is open to certain objec- A tions from the standpoint of present day converters acceptable to the trade. The industry 'has accepted one type of apparatus in' which the converter comprises but a single shell or casing, and within which are located spaced apart perforated shelves upon which catalytic material is supported. The mass of catalytic material on any one shelf is insuflicient to 'fill the entire space between shelves so that as opposed to the showing of this patent, there is a considerable ,1 distance between the top of any contact mass '75 lytic material, the production of sulphur trioxide and the next shelf, in the direction of gas flow. under commercial conditions that the latter arrangement produces a much greater efficiency of conversion. The Ferguson patent proposes to admix this air so of pipe connected between Inthoseconverter systems ment cannot be embodied therein. The present day converter systems for the 35 production of sulphuric acid find it necessary either to embed in the contact material heat exchange devices or to insert such devices between contact chambers in order to maintain the flowing gas within the limited temperature range at which conversion proceeds smoothly and efliciently.

It is, therefore, the principal object of the present'invention to devise a converter system range, in a manner specifically different from Ferguson .and without the use of the expensive and not altogether satisfactory heat exchange n devices at present adopted as standard. This M consequently lowers the initial and maintenance cost of theequipment.

. Another important object of the invention is the provision in such a system of means whereby the added an and hot sulphur-bearing gases may be thoroughly and efficiently mixed prior to their passage to the next contact mass.

The invention in its broadest aspect contemplates the mixing of one gas with another, where that other comprises a flowing stream of a com; 1

height. This passage of the two gases through,

this small aperture causes intimate contact between the two with resultant e-iiicient mixing-and ccmrningling. At the same time where the oncoming gases are comparativelyhot and the added gases are coinparativelyflcool, a heatt ansired temper ture tioning the fer takes place so that the des may be obtained by suitably propor amounts of the two gases.

As applied to a sulphuric acid converter, the invention comprises the provision of a single caslingorshell within. which is ..located a seriesaof :"sTpaced'apart perforated shelves with contactin l1 i'lo'n. these. shelvesin suchquantityas. to proea substantialspace lbetweenithe topot any contact massage th xt shlfnin the direction r U or gas new. j-Means are providedrorsupplying i sulphursdioxide. gas s "tothebottom .0: the first f this "seriesof shelxiesland,additionah means are. provided for introducing laininto the space between contact 'mas es,ta;ngnuau of th'e shell. Means arefalsolprovided beydn'd. the air inlet .ii'n.thelldirectionlof gasnqw, comprisinga. series bf baifies which form in, .efiectl n. aperture, the [width offwhichj riianytiine's its ight, through ,35 t 'ich.the onecoiningsulphur-h lng gasesand ,admii'red airpa'ssj in acircuitouspath iwith.con-

. sequent. 'efiici'ent mixing and. commi'ngling. .The er. contemplates the method of invention. iiu'rth H k fnperatingisuch a device.

k rlIn the drawing:

ii -r e a i r mma rle e tp es phuric acid I contact apparatus and associated inechanisin, .in'which the torrner, shown-an songe dtair s r "Y is a isse ;tee -re isin h 1.

Fig. 3 is. a fragmentary .sectional meleyation sh i ish ;i i ia ee i set @3 s etef amas Y Q ..ve rin inqwiw h pa t qu am r t th drawins, and asanp ying theinve t o tqa iapparatus for the production of sulphuric anhydride, .h'ot sulphurfdioxide. gasescontaining some airare .pro'duced-Iin any desired. equipment, and. pass to a waste heat boiler for. the purpose of abstracting a portion oithe' heat from the -gases, which at this stage 'arefar' above efiicient converter temperatures; with 'the' prbdueue of seem; all of which T rea t r o s l h r d qxi ean a within the conversion temp erature range, enters th qeaie app ra u hrbushlhe el. Th shs fi tempti t l l wwhich the gasesshduld e cdoi e w l b e, 1. 1e th j haracter bf theflco ita tmatriaLnfd.

The converter prop I er. comprises a shell, 01', Gasing 2, preierably' ofja cylind'rical nature, having agbpttonifiland ato held togethe1as ..by means "74 pi a, series of a s'sing ic mpletely through ,40 The 'inv'eintidn further includes the noyelarrangen'ient, combination ,and construction :1 of

arne,

the apparatus and secured at the upper and lower end by nuts 6 and '7.

Supported upon pipe spacers 8 surrounding the rods 5, is a lower perforated plate 9 adapted to support a mass of contact material 10. In the same manner, .additional.perforated shelves 9 are upported'withinthe shell 2 at suitable intervals andalso support their individual mass of contact material. It is to be noted that the quantity oi contact material on any one shelf is such that there is a considerable space between the top of such mass, andthe-bottom of the next succeeding it'shelt-imthe direction of gas flow.

Means are, provided for supplying quantities -o airor other-oxygen available gases to the shell or sing 2 and into the space betwen contact masses. This means may conveniently consist of an air iblower supplying air through the pipe 11 to a manifold 12 supplied with short lengths of pipe 13 terminating in elbows 14 within the shell, 1 and arrangedto eject the air tangentially there- C into. The. short-lengths 01, pipe, 13 may be: individually -provided with suitable valves 15 sozthat ,the quantityandflow. of incoming air ,maybecon- "trolled at yarious points. -Itis preferablethatthei point or" introduction of thisair. bev immediately adjacent. the top of each of the contact masses.

;the ;space between the top 10f; any contact i massand} the shelf; above, in the direction of, gas fiow,. are. arranged a series of baffles forcausingf. ccnnrningling of-;-the added air. and the on-coming gases before passing through: a subsequent contact -mass. These baflies- 1 may conveniently consist-of, an intermediate-imperforate circular disc oig 5 plate 16 supported- .up on' -the--.-nec essary I10 spacers 17 theplate '16 having hung therefroma ap ns red i p acebrmea s ofnuts esz hew .r s e ab s hatat erlowerbaifie nged directly abqve the, air inlets-'14 .all rext nding out ;toward ithe. goenter of- :the apxpamti s bsyQndith ase s hat. -t e a enters ,tangentiall rac-swirling action;;maybe =:secur,ed ,and fthis air will spill oyengthevinner edgeoflthe .finnula eba fle l8 t 3 .1 6- spa between the .--bafi1e and -thei-mperforate plate '16. 5 Itis desirableithat these -two, parts ,be spaced; apart :insuch relation vthat; a; slit or apeigture is provided; 'the widthajof which is many times its height. This arrange- ,rnentpauses the on-tQIIling-gases andv the enteri ing airnto ,eiiiciently contact, and commingleiwith each other. Fromthispoint: the gasesqpassgup- ,around, the outer; periphery of 1 the r =imperforate .plate; .or discv 16; between the latter. ele- .mfin landizthe dished baffle 19, and through: the nextperiorateplate and-its contact-mass. Ithas been iound thatwhere the upper baiilelQis ,dished as shcwn, there ,isan efficient distribution ,of-this-rnixed gasover; the-entire area of the. space zbet wee n contact masses. In order that the space directly; adj went the v.wall .oftheshell 2 -may= rehave its ffshare of the ,gases, the .baiiies 11978.18 spa ed lightlydrom,the;wal1-v thereof ,-whichpera, certain. arnount, of v leakage past them.

1 Fromgthe ,ab ove, it gw ill .beseen that thedesired amount of Lair may Joe introduced -into the gonrig gases as -they-leaveeach of the contact sses. .From ,this -;point ,the two gases pass through thamixingdevice. comprising the series 9f bailie s, Qwhich no t only causes efficient and tho h, mixing of.: the gases, but: permits -atthis P9, shea h /misfits ak :pl ewv ths h iretact masses, which consists in passing a mixture sult that the mixed gases passing toward the next perforated plate and its contact mass have been cooled to within the proper conversion temperature range. This operation is repeated and additional air added-as desired in order to supply the proper proportions of air and S02, and the conversion product passes out of the port 23 for further treatment as desired.

It is to be noted that this arrangement provides for an extreme flexibility of control in the temperature and proportions of gases passing to any contact mass. This constitutes a very important feature of the invention, which has not been possible heretofore.

It will also be seen that the mixing baflles cause an intimate commingling of the two gases, which is an extremely diflicult problem, particularly in a converter where its diameter is frequently as great as 10 it, while the space between the top of any contact mass and the bottom of the next perforated plate in the direction of gas flow, is not over 1 ft., and any mixing or heat transfer which takes place must be done within this short direc- T shown and described, but the invention is to be construed broadly and limited only by the scope of the claims.

I claim:

1. A method of mixing one gas with a moving J body of another, which consists in introducing the first gas to the body of the second tangentially thereof, so as to produce a swirling action, and subsequently passing the two gases through an aperture, the width of which is many times greater than its height, to cause mixing and commingling of the two gases.

2. A method of mixing air with a moving body of hot S02, which consists in introducing the air to the body of S02 tangentially'so as to produce a swirling action, and subsequently passing the mixture of S02 and air in a circuitous path through an aperture, the width of which is many times greater than its height.

3. A method of operating a contact converter for the conversion of S02 to S03, where the gases pass successively through a series of contact masses, which consists in passing a mixture of air and S02 through one of said masses, subsequently introducing relatively cool air to said gas, passing the mixture through an aperture,

the width of which is many times greater than its height, whereby the gas and added air are thoroughly commingled and the gas is cooled,

.and uniformly redistributing the commingled and cooled mixture for passage to another contact mass.

4. A method of operating a contact converter for the conversion of S02 to S03, where the gases pass successively through a series of conof air and S02 through one of said masses, subsequently introducing relatively cool air to said gas, passing the mixture through an aperture, the width of which is many times greater than its height, whereby the gas and added air are thoroughly commingled and the gas is cooled, passing the commingled and cooled mixture to another contact mass, and repeating the air addition in the same manner prior to the passage of the gas stream tact mass.

through each subsequent conin, a contact mass on each shelf spaced from the shelf above, means to introduce air from out-- side the shell into the space between shelves; and means beyond the air introduction means in the directionof gas flowin additionto the shelves and their contact masses, to cause commingling of the on-coming gas and the added air.

6. A contact converter comprising a shell, a series of perforated spaced apart shelves there in, a contact mass on each shelf spaced from the shelf above, a gaseous reactant inlet between shelves, an annular baiile'immedi'ateiy above the reactant inlet, an imperforate plate above the baille of less diameter than the shell whereby the gas from the lower contact mass and the added gaseous reactant pass between the baffle and the plate and between the plate periphery and the shell before reaching'the contact mass above.

'7. A contact converter comprising a shell, a series of perforated spaced apart shelves therein, a contact mass on each shelf spaced from the shelf above, a gaseous reactant inlet between shelves, an annular baflle immediately above the reactant inlet, an imperforate plate above the baflle of less diameter than the shell, the plate being in close proximity to the baiile, whereby the gas from the lower contact mass and the added gaseous reactant pass between the baflie and the plate and between the plate periphery and the shell before reaching the contact mass above.

8. A contact converter comprising a shell, a series of perforated spaced apart shelves therein, a contact mass on each shelf spaced from the shelf above, a gaseous reactant inlet between shelves, an annular baiile immediately above the reactant inlet, an imperforate plate above-the bafile of less diameter than the shell and a second annular baffle immediately above the plate, whereby the gas from the lower contact mass and the added gaseous reactant pass through a circuitous path before reaching the contact mass above.

9. A contact converter comprising a shell, a V

series of perforated spaced apart shelves therein, a contact mass on each shelf spaced from the shelf above, a gaseous reactant inlet between shelves, an annular baiiie immediately above the reactant inlet, an imperforate plate above the baffle of less diameter than the shell and a second dished annular bafile immediately above the thus forming an aperture of great width as comif 1 pared to its height, and a circuitous path whereby the gas from the lower contact mass and the added gaseous reactant pass through this circuitous path before reachingv the contact mass above.

11. A contact converter comprising, a shell, a series of perforated spaced apart shelves therein, a contact mass on each shelf spaced from the shelf above, a gaseous reactant inlet between 1 shelves, an annular baffle immediately above the reactant inlet, an imperfcrate plate above the baflle of less diameter than the shell and a second annular bafile immediately above the plate, the baflles being in close proximity to the plate,

WILLIAM L. SPALDING. 1 

